1. Field
This technique relates to a control technique of a RAID controller regarding recovery from a write error in writing data to a disk.
2. Description of the Related Art
A RAID (redundant arrays of inexpensive (independent) disks) is a typical disk array device. The RAID can construct an inexpensive, highly-reliable storage system. In particular, RAIDs 5 and 6 have been widely used. The RAIDs are very useful devices.
However, even a RAID system configured by, for example, the RAIDs 5 and 6 has a problem that would occur if a RAID controller successfully writes data to a disk but fails to write parity data corresponding to the data to the disk. In such a case, the RAID controller continues to store the parity data in a parity buffer until succeeding in a retry to write the parity data to the disk. Meanwhile, the resource of the parity buffer is limited.
Therefore, if the RAID controller sequentially receives a new write command from a host computer or accepts high-load write processing while keeping the parity data in the parity buffer, a capacity of the parity buffer runs short, resulting in a problem that the RAID controller makes an error reply to the host computer (job_abend).
Japanese Laid-open Patent Publication Nos. 2006-252414 and 2003-167688 disclose techniques regarding the RAID.